1. Field of the Invention
This invention relates to a chemical mechanical polishing (CMP) apparatus. In particular, the present invention relates to a CMP apparatus with temperature control for improving polishing uniformity.
2. Description of the Related Art
The CMP process is a technique frequently for planarizing the surfaces of insulating film and conductive film on a semiconductor substrate or filling a conductive film only in trenches or grooves.
A wafer carrier is used in the CMP apparatus to hold the wafer with the guide ring, and prevent the wafer from slipping. The wafer faces the polishing pad dispersed with polishing slurry. The polishing pad is supported by a rotatable platen.
In general, a CMP process involves mechanically polishing a thin, flat semiconductor wafer by holding and rotating the wafer against a polishing platen under controlled parameters, such as rotational speed, down force, pressure, temperature, time, and chemical conditions. However, these parameters cannot reduce polishing difference between the center and edge of the wafer, especially problematic, since, after polishing, the edge of the wafer has higher topography. In order to resolve this problem, multiple pressure zones are provided to enhance the polishing efficiency at the edge to improve the uniformity of the wafer, in cases such as U.S. Pat. No. 5,941,758 (Mack) and U.S. Pat. No. 6,033,987 (Lin et al.). However, the pressure from center to edge is not continuous, and the whole polishing uniformity cannot be efficiently resolved.
Recently, temperature parameters have been used to control the CMP process, such as in U.S. Pat. Nos. 5,196,353, 6,120,347, 6,261,151 taught by Sandhu, including the steps of chemically mechanically planarizing a wafer while simultaneously detecting a temperature of the wafer to develop a thermal image which can be analyzed to control the (CMP) process parameters. In addition to use in developing a thermal image of the wafer developed during the (CMP) process, such temperature differentials can be used to detect planar end points on the wafer.
In U.S. Pat. No. 6,227,939, Monroe adjusts the temperature of the wafer carrier and the platen to improve the uniformity of the wafer.
In U.S. Pat. No. 5,873,769, Chiou adjusts the temperature of the circular segments of the wafer carrier and the platen to improve the uniformity of the wafer.
The object of the present invention is to provide a CMP apparatus with temperature control to improve the uniformity of the wafer.
To achieve the above-mentioned object, a CMP apparatus with temperature control is provided in the present invention.
According to a first aspect of the invention, the CMP apparatus comprising: a platen; a carrier holding a wafer against the platen; a guide ring disposed at the rim of the carrier to mount the wafer thereon; and a heater disposed in the guide ring to heat the edge of the wafer. The temperature of the heater is set between 20xc2x0 C. and 60xc2x0 C.
According to a second aspect of the invention, the CMP apparatus comprising: a platen; a carrier holding a wafer against the platen; a guide ring disposed at the rim of the carrier to mount the wafer at the carrier; and a heater disposed in the carrier to increase the temperature from center to edge. The temperature of the heater is set between 20xc2x0 C. and 60xc2x0 C.
According to a third aspect of the invention, the CMP apparatus comprising: a platen; a polishing pad on the platen; a slurry supplied to the polishing pad; a carrier holding a wafer against the platen and contacting the polishing pad; and a heater for heating the slurry, wherein the temperature of the slurry increases from center to edge of the wafer. The temperature of the heater is set between 20xc2x0 C. and 60xc2x0 C.